diff --git a/src/cpp_token.cpp b/src/cpp_token.cpp
index 8664f33..e1b1df1 100644
--- a/src/cpp_token.cpp
+++ b/src/cpp_token.cpp
@@ -216,7 +216,7 @@ namespace
         for (; is_digit(*ptr) || *ptr == '\''; ++ptr)
             if (*ptr != '\'')
                 result += *ptr;
-        DEBUG_ASSERT(result.back() != '\'', detail::assert_handler{});
+        DEBUG_ASSERT(result.empty() || result.back() != '\'', detail::assert_handler{});
         return result;
     }
 
@@ -569,7 +569,7 @@ namespace
 
         return type_safe::nullopt;
     }
-}
+} // namespace
 
 cpp_token_string cpp_token_string::tokenize(std::string str)
 {
@@ -605,7 +605,7 @@ namespace
     {
         return std::isalnum(c) || c == '_';
     }
-}
+} // namespace
 
 std::string cpp_token_string::as_string() const
 {
diff --git a/src/libclang/libclang_parser.cpp b/src/libclang/libclang_parser.cpp
index 3edecd7..fe13f96 100644
--- a/src/libclang/libclang_parser.cpp
+++ b/src/libclang/libclang_parser.cpp
@@ -91,7 +91,7 @@ namespace
         }
         return result;
     }
-}
+} // namespace
 
 libclang_compile_config::libclang_compile_config()
 : compile_config({}),
@@ -150,7 +150,7 @@ namespace
             // relative w/o separator
             return dir.std_str() + file;
     }
-}
+} // namespace
 
 void detail::for_each_file(const libclang_compilation_database& database, void* user_data,
                            void (*callback)(void*, std::string))
@@ -226,7 +226,7 @@ namespace
             // else skip argument
         }
     }
-}
+} // namespace
 
 libclang_compile_config::libclang_compile_config(const libclang_compilation_database& database,
                                                  const std::string&                   file)
@@ -303,7 +303,12 @@ void libclang_compile_config::do_set_flags(cpp_standard standard, compile_flags
     }
 
     if (flags & compile_flag::ms_compatibility)
+    {
         add_flag("-fms-compatibility");
+        // see https://github.com/foonathan/cppast/issues/46
+        define_macro("_DEBUG_FUNCTIONAL_MACHINERY", "");
+    }
+
     if (flags & compile_flag::ms_extensions)
         add_flag("-fms-extensions");
 }
@@ -484,7 +489,7 @@ namespace
         clang_getPresumedLocation(loc, nullptr, &line, nullptr);
         return line;
     }
-}
+} // namespace
 
 std::unique_ptr<cpp_file> libclang_parser::do_parse(const cpp_entity_index& idx, std::string path,
                                                     const compile_config& c) const try
diff --git a/src/libclang/preprocessor.cpp b/src/libclang/preprocessor.cpp
index 9ccdcad..8d8564c 100644
--- a/src/libclang/preprocessor.cpp
+++ b/src/libclang/preprocessor.cpp
@@ -88,8 +88,7 @@ namespace
     }
 
     // parse and log diagnostic
-    // returns true if a diagnostic was logged due to a bug, but it is otherwise harmless
-    bool log_diagnostic(const diagnostic_logger& logger, const std::string& msg)
+    void log_diagnostic(const diagnostic_logger& logger, const std::string& msg)
     {
         auto ptr = msg.c_str();
 
@@ -105,13 +104,7 @@ namespace
         while (*ptr && *ptr != '\n')
             message.push_back(*ptr++);
 
-        // see https://github.com/foonathan/cppast/issues/46
-        auto harmless_diag =
-            message.find("invalid filename for #line directive") != std::string::npos;
-
         logger.log("preprocessor", diagnostic{std::move(message), std::move(loc), sev});
-
-        return harmless_diag;
     }
 
     // parses missing header file diagnostic and returns the file name,
@@ -362,8 +355,6 @@ namespace
     std::string write_macro_file(const libclang_compile_config& c, const std::string& full_path,
                                  const diagnostic_logger& logger)
     {
-        auto expect_bad_exit_code = false;
-
         std::string diagnostic;
         auto        diagnostic_logger = [&](const char* str, std::size_t n) {
             diagnostic.reserve(diagnostic.size() + n);
@@ -373,7 +364,7 @@ namespace
                 else if (*str == '\n')
                 {
                     // consume current diagnostic
-                    expect_bad_exit_code |= log_diagnostic(logger, diagnostic);
+                    log_diagnostic(logger, diagnostic);
                     diagnostic.clear();
                 }
                 else
@@ -396,7 +387,7 @@ namespace
 
         auto exit_code = process.get_exit_status();
         DEBUG_ASSERT(diagnostic.empty(), detail::assert_handler{});
-        if (exit_code != 0 && !expect_bad_exit_code)
+        if (exit_code != 0)
             throw libclang_error("preprocessor (macro): command '" + cmd
                                  + "' exited with non-zero exit code (" + std::to_string(exit_code)
                                  + ")");
@@ -438,7 +429,7 @@ namespace
                         expect_bad_exit_code = true;
                     }
                     else
-                        expect_bad_exit_code |= log_diagnostic(logger, diagnostic);
+                        log_diagnostic(logger, diagnostic);
 
                     diagnostic.clear();
                 }